The effect of concrete strength and reinforcement on toughness of reinforced concrete beams

The objective pursued with this work includes the evaluating of the strength and the total energy absorption capacity (toughness) of reinforced concrete beams using different amounts of steel-bar reinforcement. The experimental campaign deals with the evaluation of the threshold load prior collapse, ultimate load and deformation, as well as the beam total energy absorption capacity, using a three point bending test. The beam half span displacement was measured using a displacement transducer, and the applied force was monitored using a load cell. The tested samples consists on a set of ten reinforced concrete beams having three different levels of steel-bar-reinforcement percentages and four different concrete compositions (i.e., giving rise to a different values of concrete strength). It was observed that the most influential parameter in the beams energy absorption capacity is the amount of steel-bar reinforcement. The results have presented good agreement between themselves. In fact, for beams with a given concrete compressive strength, a decrease in beam's deformation was measured for higher steel-bar-reinforcement percentages. Moreover, the results had shown that for a particular steel-bar-reinforcement percentage, the concrete compressive strength have also influence in the total energy absorption capacity of the beams.